In industrialized societies the occurrence of hazardous materials spills has become common place and various technologies have been developed to deal with these types of situations. Such spills sometimes occur at sea, but more often occur on land or even underneath the ground surface. For example, underground gasoline tanks may leak or solvents used in industrial processes may be discharged illegally into waste water or sumps or directly onto the ground. In any case, the hazardous material, typically a volatilizing organic compound, may propagate great distances through the ground and even enter ground water aquifers. It will be appreciated that the resulting environmental impact may be devastating.
Many hazardous materials found at these sites are stable, do not undergo environmental degradation at reasonably fast rates, have high boiling points and are considered toxic at very low concentration levels. Accordingly, such materials can bio-accumulate in various species of the food chain at concentrations higher than what is found in the environment.
Several techniques have been proposed to deal with the treatment and recovery of such volatilizing organic compounds and other contaminants. These include everything from various vacuum techniques, where soil is removed and treated, to on-site treatment of contaminated soil. Another technique is pyrolysis, which has been used for the thermal destruction of many contaminated materials. Known techniques, however, suffer from a range of shortcomings.
One such shortcoming is the high costs associated with removing and cleaning contaminated soil by means of commercially available techniques and systems, because of the inherent characteristics and operating parameters of these techniques and systems.
Another shortcoming is that known treatment techniques often do not provide an effective solution to the problem, as it is inadequate to remove the hazardous materials completely, leaving behind small amounts of the hazardous materials even in the treated and “cleaned” soil, which continues to be a potential source of an environmental disaster.
Also, with known soil cleaning techniques often only a limited volume of ground soil can be treated at a time. This limitation not only increases costs as a result of repeated cleaning cycles, as well as with respect to the need for safe storage and transport of contaminated soil, but also increases the time that it takes to clean a contaminated area sufficiently.
A further disadvantage of many treatment options is that the contaminated materials are heated to temperatures which vaporise and/or thermally destroy the contaminants. These processes do not allow for the recovery and/or potential re-use of the contaminants.
A need exists for a method and apparatus for efficiently and rapidly removing hazardous materials, including volatilizing organic compounds, from contaminated material without excessive contaminant discharge to the atmosphere, and for doing so at a reasonable cost, while at the same time recovering re-usable materials.